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arXiv 0802.3345astro-ph
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利用WMAP偏振数据分离反常辐射和同步辐射

Separation of anomalous and synchrotron emissions using WMAP polarization data

M. -A. Miville-Deschenes, N. Ysard, A. Lavabre, N. Ponthieu, J. F. Macias-Perez, J. Aumont, J. P. Bernard

摘要:

这项研究的主要目标是使用来自WMAP强度和偏振数据的信息来分离银河系成分,重点是同步辐射和异常辐射。我们的分析是在23 GHz的信噪比是最高的和CMB地图的估计是不太重要的。我们的同步辐射强度的估计是基于一个外推的Haslam 408 MHz的数据与空间变化的光谱指数的约束下的WMAP 23 GHz的偏振数据和双对称螺旋模型的银河系磁场的湍流部分以下-5/3的幂律谱。23 GHz的极化数据被认为是兼容的磁场与俯仰角p=-8.5度和振幅的湍流部分的磁场的0.57倍的本地值的字段,在协议中发现使用旋转措施的恒星和偏振消光尘埃。从极化数据和我们的磁场模型获得的408 MHz和23 GHz之间的同步加速器光谱指数的平均值为β =-3.00,具有有限的空间变化,标准偏差为0.06。当从WMAP强度数据中去除热尘埃、自由-自由和同步辐射时,剩余的异常发射与热尘埃发射高度相关,其光谱与自旋尘埃模型一致。考虑一个经典的大尺度银河系磁场模型,我们表明,偏振数据的WMAP是有利于一个软同步辐射强度与408 MHz的数据高度相关。此外,WMAP的偏振和强度数据的组合带来了强有力的证据,在20-60 GHz范围内的非偏振旋转尘埃排放的存在。

英文摘要:

The main goals of this study is to use the information from both WMAP intensity and polarization data to do a separation of the Galactic components, with a focus on the synchrotron and anomalous emissions. Our analysis is made at 23 GHz where the signal-to-noise ratio is the highest and the estimate of the CMB map is less critical. Our estimate of the synchrotron intensity is based on an extrapolation of the Haslam 408 MHz data with a spatially varying spectral index constrained by the WMAP 23 GHz polarization data and a bi-symmetrical spiral model of the galactic magnetic field with a turbulent part following a -5/3 power law spectrum. The 23 GHz polarization data are found to be compatible with a magnetic field with a pitch angle p=-8.5 degrees and an amplitude of the turbulent part of the magnetic field 0.57 times the local value of the field, in agreement with what is found using rotation measures of pulsars and polarized extinction by dust. The synchrotron spectral index between 408 MHz and 23 GHz obtained from polarization data and our model of the magnetic field has a mean value of Beta=-3.00 with a limited spatial variation with a standard deviation of 0.06. When thermal dust, free-free and synchrotron are removed from the WMAP intensity data, the residual anomalous emission is highly correlated with thermal dust emission with a spectrum in agreement with spinning dust models. Considering a classical model of the large scale Galactic magnetic field, we show that the polarization data of WMAP are in favor of a soft synchrotron intensity highly correlated with the 408 MHz data. Furthermore the combination of the WMAP polarization and intensity data brings strong evidence for the presence of unpolarized spinning dust emission in the 20-60 GHz range.

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